I've been working as the Social Media Editor and a staff writer at Forbes since October 2011. Prior to that, I worked as a freelance writer and contributor here. On this blog, I focus on futurism, cutting edge technology, and breaking research. Follow me on Twitter - @thealexknapp. You can email me at aknapp@forbes.com

How Lead Caused America's Violent Crime Epidemic

Starting in the 1960s, America saw a huge increase in levels of violent crime that peaked in the early 1990s, then steadily declined, and continues to decline today. All kinds of theories have been promulgated to explain this peak and decline in crime, and plenty of politicians in the 1990s took credit for it. But in what I personally consider to be a tour de force of journalism, Kevin Drum of Mother Jones has summarized all of the available research. All of it points to one simple idea: violent crime rose as a result of lead poisoning because of leaded gasoline. It declined because of lead abatement policies.

There are three basic reasons why this theory should be believed. First, as Drum points out, the numbers correlate almost perfectly. “If you add a lag time of 23 years,” he writes. “Lead emissions from automobiles explain 90 percent of the variation in violent crime in America. Toddlers who ingested high levels of lead in the ’40s and ’50s really were more likely to become violent criminals in the ’60s, ’70s, and ’80s.”

Second, this correlation holds true with no exceptions. Every country studied has shown this same strong correlation between leaded gasoline and violent crime rates. Within the United States, you can see the data at the state level. Where lead concentrations declined quickly, crime declined quickly. Where it declined slowly, crime declined slowly. The data even holds true at the neighborhood level – high lead concentrations correlate so well that you can overlay maps of crime rates over maps of lead concentrations and get an almost perfect fit.

Third, and probably most important, the data goes beyond just these models. As Drum himself points out, “if econometric studies were all there were to the story of lead, you’d be justified in remaining skeptical no matter how good the statistics look.” But the chemistry and neuroscience of lead gives us good reason to believe the connection. Decades of research has shown that lead poisoning causes significant and probably irreversible damage to the brain. Not only does lead degrade cognitive abilities and lower intelligence, it also degrades a person’s ability to make decisions by damaging areas of the brain responsible for “emotional regulation, impulse control, attention, verbal reasoning, and mental flexibility.”

The bottom line, as Drum points out, is that “even moderately high levels of lead exposure are associated with aggressivity, impulsivity, ADHD, and lower IQ. And right there, you’ve practically defined the profile of a violent young offender.”

I’ve barely scratched the surface of Drum’s excellent article, and I’d seriously encourage you to hop over to Mother Jones right now and read the whole thing. I’ve been reading Drum for years and he’s been blogging about this topic for a long time. Indeed, I’ve been convinced of the lead/crime hypothesis for years thanks to Drum’s writing. But this article is a masterpiece. Read it. Talk about it. It’s an important piece of journalism.

In particular, it’s important because this is precisely the kind of problem that people are uncomfortable about believing. It’s hard for us to see the link between cause and effect when there’s a 20+ year gap between one and the other. Additionally, none of us like thinking that our autonomy as human beings can be destroyed by forces beyond our control that we can’t even see.

But such time lags between cause and effect do exist. Invisible molecules like tetraethyl lead can do us great harm. We need to understand this. It’s not enough to know this as an interesting fact. We have to know in our guts that these types of things are possible, because this is far from the only problem like it. And that kind of deep understanding that these problems are possible are what’s necessary to motivate us as people to do something about it.

Post Your Comment

Post Your Reply

Forbes writers have the ability to call out member comments they find particularly interesting. Called-out comments are highlighted across the Forbes network. You'll be notified if your comment is called out.

Comments

Hi Alex – I emailed you – my name is Tamara Rubin and I am the mother of a lead-poisoned child that Kevin interviewed for his article. I am making a documentary feature film on the subject – called MisLead: America’s Secret Epidemic – www.MisLeadMovie.com has some of our sample footage, it is a project of my 501(C)3 Nonprofit, the Lead Safe America Foundation ( www.leadsafeamerica.org ) and people can be in touch with specific questions about the issue on facebook at http://www.Facebook.com/MisleadMovie – I’d love to talk to you some more about this from a parents perspective if you have some time! Plus you can check out some of my rough-cut footage and some clips from my interview with Noam Chomsky on the film’s website.

I’m not fond of pointing this out, but when you look at the actual crime data by race, it’s pretty obvious that violent crime has been in general decline since 1980 (which pretty much wrecks their “23 year lag”). Unfortunately, black communities were hit hardest by the crack epidemic, and saw a HUGE spike in violent crime between 1984 and 1994 — but if you magically erase those years, you find a tidy downward slope, starting in 1980 and extending all the way to 2000, where it levels off.

I’m all for lead abatement, but these people seem to have an agenda, and they seem conveniently to ignore social issues that we know led to increased violence. Between 1965 and 1980, for example, we had tens of thousands of Vietnam War vets struggling to fit into normal society, we had the militant hippies bombing govt. buildings, and we had the fallout from the civil rights movement and the death of its leaders (basically a bunch of very unhappy young people). Guess what? Between 1965 and 1980 violent crime reached its all-time peak. Things started to cool down in 1980, but in 1984 crack was dumped into our poorest neighborhoods, which started the violence back up again. The authors of these studies happily mix poor and middle-class crime statistics to give you the impression that the violence was pervasive, when in reality, it was neatly confined to the groups experiencing the greatest amount of stress.

I’m totally for lead abatement, btw, but come on, at least try and look at the big picture.

This sounds like junk science to me. White toddlers who grew up in urban areas and in urban areas of foreign first world countries were also exposed to leaded gasoline. But Detroit’s crime rate has been much higher than Toronto’s for as long as I can remember. Did anyone bother to look at the results for toddlers who grew up on one side of the Detroit/Gross Point Park boundary versus the other?

The best explanation I have run across for the drop in violent crime starting in the mid-1990′s is the effect of Roe v. Wade. Black teenage girls had better access to abortion.

If you dig into Drum’s article, you’ll see that there is good reason to doubt the abortion-crime connection. Moreover, yes, there are definitely differences between neighborhoods. Poor neighborhoods tend to have higher lead concentrations.

Junk science? I suppose you read the study linked in the Mother Jones article? No? I thought not.

This is not simply a case of some random stat lining up with some other random stat. As far as the social sciences go, this is about as solid as you can get. Chemistry provides a mechanism to describe how lead reacts with organic compounds, neuroscience specifically how lead exposure in fetuses and young children impact development, and econometrics gives us a positive correlation between lead exposure and crime rates that is consistent regardless of time period (the correlation also happened in the early 20th century with the rise and fall of lead paint), culture, socioeconomic status, country, region, state, all the way down to neighborhood levels.

If that is junk science, then science as a discipline is completely useless.

Another reasonable explanation could be that during this same period of time incarceration levels rose, police methods of catching criminals improved and in one of the most obvious relations of all time, the thugs killed each other off.

In fact, look at Chicago where an open air massacre occurs every week which makes Newtown look tame by comparison.

As someone else pointed out, children from middle class backgrounds whose vehicles used the same leaded gas, did not go out and gun people down in the street.

By the way, lead was banned before Adam Lanza was born and it did nothing to stop or help him.

Posting this ridiculous nonsense is typical of liberals who always want to justify their actions with pseudo science and this isn’t even pseudo science.

In the meantime not one word of complaint from Mother Jones about out of control liberalism which has created killing zones in almost every major city controlled by liberals.

With Mother Jones, like all liberal news sources, facts are what you believe to support your position then you herald it as new found science although there is little to support it.

Did you read the myriad number of studies that were collected on this subject and that Mr. Drum helpfully linked to? Did you read the evidence he presented indicating that the causes you suggest – namely, increased incarceration?

Alex: Thanks for the response. But if what you write is accurate give me a brief explanation for out of control crime within our inner cities. Chicago is a well publicized killing field. If lead had anything to do with crime rates it’s more likely this type of lead. You should read Forbes once in awhile: http://www.forbes.com/sites/peterferrara/2012/12/28/assault-weapon-is-just-a-pr-stunt-meant-to-fool-the-gullible/ . . . .. . because the presence of guns that can be used in self defense stops the commission of the more violent crimes, such as murder.

This unparalleled scholarship has swept the states with newly enacted “concealed carry” laws. These laws require local authorities to issue permits to carry concealed handguns to those who meet the specified qualifications, known as “shall issue” laws. Alternative state laws authorize local authorities with the discretion to issue such concealed carry permits, known as “may issue’ laws. In the early 1980s, just 8 states had any such right to carry laws. Today, 39 states have shall issue laws and 9 more have may issue laws. That leaves just two states, Illinois and Wisconsin, that completely ban citizens from carrying concealed handguns, and the Seventh Circuit just ruled the Illinois ban to be unconstitutional under the Second Amendment.

As a result, by 2007 about 5 million Americans held permits to carry concealed handguns. Lott’ s Third Edition published in 2010 includes regressions that show these concealed carry laws result in:

“large drops in overall violent crime, murder, rape, and aggravated assault that begin right after the right to carry laws have gone into effect. In all those crime categories, the crime rates consistently stay much lower than they were before the law. The murder rate for these right to carry states fell consistently every year relative to non-right-to-carry states.”

A quick look shows that Chicago has one of the highest concentrations of lead – and therefore highest rates of lead poisoning – in the country. See, for example, http://bit.ly/SPKcuK.

There’s still a lot of lead out there.

As for Dr. Lott’s work, it has yet to be replicated by other social scientists. (Indeed, there’s some suggestion that his methodology is flawed.) Indeed, Lott sued someone who claimed that Lott’s work hadn’t been replicated, and the courts found against Lott.

That’s not to say that Lott is wrong – a National Academy of Sciences report a couple of years ago said that there wasn’t enough evidence available yet to side with either Lott or his critics on this particular issue.

In this particular case, given that Chicago still has lots of lead exposure, it seems to be the more likely cause of higher crime rates there.